A) Field of the Invention
The present invention relates to a semiconductor light emitting device, and more particularly to a semiconductor light emitting device capable of narrowing the spread of a spectrum of radiated light.
B) Description of the Related Art
An infrared light emitting device can be manufactured by using semiconductor material having a band gap in an infrared range. JP-A-2002-344013 discloses a light emitting device for infrared spatial optical communications, using an InGaAs strain quantum well layer as an active layer. This light emitting device has the InGaAs strain quantum well layer sandwiched by a pair of AlGaAs carrier confinement layers, and this lamination structure is sandwiched by a p-type AlGaAs clad layer and an n-type AlGaAs clad layer.
A radiation spectrum of the light emitting device disclosed in JP-A-2002-344013 has a maximum intensity in an infrared wavelength range. However, a skirt of the spectrum spreads to the visual range. Therefore, radiated light from the light emitting device is slightly reddish. If radiated light contains visual light, the usage of the light emitting device is restricted. For example, this light emitting device cannot be used in the field prohibiting emission of visual light. If the spread of a spectrum of light radiated from the light emitting device can be narrowed, it is possible to suppress the generation of visual light.